A quarter-million dollars came from the head of Suffolk Construction, a Boston-based builder betting big on a New York City expansion.

Another $150,000 arrived from the chairman of Vornado Realty Trust, who is searching for a way to revive a stalled Midtown Manhattan redevelopment so important that he once called it his “promised land.”

DoorDash, the food delivery service lobbying City Hall on regulations that could disrupt its business model, chipped in a staggering $1 million.

The donations make up just a fraction of the checks from New York business leaders, billionaires and special interest groups pouring into a super PAC boosting Andrew M. Cuomo, the favorite in the Democratic primary for mayor on June 24.

With $10 million raised so far, the super PAC, Fix the City, is already the single largest outside spending force in New York City’s political history, surpassing a record set in 2021. It has spent multiples more on ads than any campaign in the race, blanketing New Yorkers’ screens in paeans to the former governor.

The next biggest candidate super PAC, set up to back Assemblyman Zohran Mamdani, a democratic socialist who is second in recent polls, has 1/50th of the funds.

Many of Fix the City’s donors are longtime Cuomo supporters who share his moderate policy views, or fear what Mr. Mamdani’s tax-the-rich policies would do. Among them are Barry Diller, the media mogul ($250,000); Billy Joel, the musician ($50,000); Bill Ackman, the investor ($250,000); and Kenneth Langone, the Home Depot founder ($50,000).

But millions of dollars more have arrived from labor unions, tech companies, real estate developers and landlords who have a direct financial stake in the election’s outcome — grand gestures that, while legal, raise pressing ethical questions about the motivations behind their generosity.

The potential conflicts can be seen in the donations from real estate, a multibillion industry that relies on City Hall to approve land use agreements and zoning variances that can make or break a project. Many of the city’s largest developers and landlords, or their executives, have donated five- or six-figure sums, including Related Companies, the Durst Organization, Two Trees Management Company, RXR and Vornado, whose Midtown development plan Mr. Cuomo supported as governor.

Many of the donations came after Mr. Cuomo made a rare appearance at the Real Estate Board of New York, where Politico reported that he expressed regret for signing rent reforms as governor that landlords bitterly opposed.

Rich Azzopardi, a spokesman for Mr. Cuomo, was adamant that “no contribution of any amount will have any influence on a government decision of any kind.”

Liz Benjamin, a spokeswoman for the super PAC, said the group had made no assurances to donors. “Donors have supported Fix the City because they know that Andrew Cuomo has the right experience and the right plans for New York City,” she said.

But New York has a long history of pay-to-play behavior, in which individuals and businesses shower politicians with large campaign donations in hopes of gaining access and preferential treatment.

The issue is hardly abstract for New Yorkers deciding whether to replace Mayor Eric Adams. The incumbent was indicted last fall on federal corruption charges that accused him of providing political favors for campaign donors. The Trump administration later dropped the charges, but only after prosecutors handling the case accused their superiors of striking a corrupt bargain with the mayor.

Government watchdog groups and other Democrats in the race have sounded alarms that some donors now at least appear to be seeking favor with Mr. Cuomo, a notorious micromanager whose fund-raising practices drew near constant scrutiny as governor.

“This is about tithing to the king and giving the king his share in case you need to call on him for help or protection,” said John Kaehny, executive director of Reinvent Albany, a leading watchdog group.

“There’s not necessarily a glaring quid pro quo,” he added. “It’s insurance and access.”

The city instituted a campaign matching funds program decades ago to try to limit the influence of big donors. In exchange for agreeing to strict limits on how much they can raise directly — $2,100 from most individuals; $400 from people with city contracts — well-backed candidates like Mr. Cuomo can tap into millions of dollars in public matching funds.

But the rise of super PACs has reinvigorated New York’s transactional culture. Since the Supreme Court’s 2010 Citizens United decision, the groups are allowed to raise and spend unlimited sums, so long as they operate independently from the campaigns they support.

In Mr. Cuomo’s case, though, Fix the City can be hard to distinguish from his official campaign. It is run by Steven M. Cohen, a member of Mr. Cuomo’s inner circle for decades, and its messaging closely mirrors that of the official campaign.

A New York City Campaign Finance Board investigation determined that because the campaign’s messaging was so similar to the super PAC’s, they were most likely colluding. The board penalized Mr. Cuomo by withholding $1.3 million — equal to the cost of one of the PAC’s commercials — from the amount of public matching funds Mr. Cuomo was expecting. The candidate is appealing.

As of last week, Fix the City had collected 38 contributions of $100,000 or more, including from individuals and companies who contract with the city. The group was expected to report another $250,000 contribution on Monday from Mark Gorton, the founder of Robert F. Kennedy Jr.’s presidential super PAC, according to a person familiar with the plans. Mr. Gorton has said “that 9/11 was orchestrated by the U.S. government.”

At least 16 donations can be tied to individuals Forbes magazine identified as billionaires (that does not include four donations from Rockefellers).

Some are motivated by Mr. Cuomo’s tough-on-crime approach or support for Israel. Many executives, even those who clashed with him when he was governor, say Mr. Cuomo is the most business-friendly candidate in the race. Several have also donated to President Trump.

“Folks are looking for somebody with strong leadership and a perceived sense of getting things done,” said Carlo Scissura, president of the New York Building Congress, a trade organization. “He’s a known entity to this world.”

But privately, business leaders and political operatives also keep mental lists of which companies, unions and executives want what from the mayor, who oversees a $115 billion annual budget and can help broker labor agreements.

Fix the City received $250,000 from Halmar International, a public works company that has had contracts with the city and state, and has a pending proposal to redevelop Penn Station.

The New York City carpenters’ union donated $100,000. A consortium of smaller building trade unions gave $250,000.

In addition to the donation from Suffolk Construction’s chairman, its executive vice president, Nick Dhimitri, serves on Fix the City’s board. He did not respond to a request for comment about the company’s giving. James L. Nederlander, a Broadway theater owner and producer, contributed $125,000.

Lyft, the ride-sharing platform that has a stake in how the city regulates for-hire vehicles, chipped in $15,000.

DoorDash, Fix the City’s single largest donor, has a clearer wish list from City Hall. It is lobbying around legislation to allow it to charge restaurants higher fees, as well as bills related to tipping rules and minimum wage requirements.

John Horton, DoorDash’s head of public policy for North America, told Politico that it believed Mr. Cuomo would be the best candidate to “prioritize practical, pro-local economy solutions.”

The contribution is one of two that have drawn extra scrutiny. The other is a $100,000 contribution from Fisher Brothers Management Company, a real estate firm that a decade ago became a poster case for the risks of money in politics.

At the time, Mr. Cuomo, then the governor, had set up a high-profile commission to root out corruption in state politics. When that Moreland Commission panel began investigating whether his own real estate donors, including Fisher Brothers, received special tax treatment from the state, Mr. Cuomo disbanded it. Publicly, he credited an agreement by the Legislature to adopt new ethics rules, but the fallout was the biggest scandal of his first term.